The Neurochemistry Core is a dual function core that will support the research efforts ofthe Projects by providing services while at the same time developing new tools and datasets that will ultimately inform each ofthe Projects. The core will provide basic histology services to document probe placements for Projects 1 and 2, and will perform quantitative oxytocin receptor (OXTR) autoradiography in rats and voles for Project 1. Th13 Core will also provide Projects 2 and 3 with novel potent and selective OXTR antagonists for their studies in nonhuman primates. In addition, the Core will play a critical role in delineating the neuroanatomical localization of OXTR in the primate brain (currently not understood). This knowledge is essential for understanding the neural mechanisms by which oxytocin (OT) modulates social cognition in Projects 2 and 3. We will use a three pronged approach for mapping the OXTR in rhesus monkey brain. First, a validated RT-PCR technique will be used to map the location of OXTR in amygdala (Amy) subnuclei as well as to determine the neuronal phenotype of OXTR neurons after single cell recording. Second, we will work to improve the selectivity of receptor autoradiography procedures in primate tissue. Finally we will continue our effort to develop and validate novel PET ligands for in vivo imaging of OXTR in living brains. If successful, the PET ligands will contribute directly to the goals of Project 2 and 3 and may ultimately be used to inform the human studies in Project 4. These aims and the functions and services that they support are essential for the integration of research designs and interpretation of findings across projects and will provide for the first time an understanding of the neural distribution of OXTR in the primate brain. The novel OXTR antagonists and PET' ligands will have a tremendous benefit for the entire research community investigating the role of OT on social behavior.